This year marks the 100th anniversary of Willa Cather's "O Pioneers!," the first of her novels set on the Nebraska plains, a work whose thoroughly American vision and simple language helped release this country's literature from obeisance to European taste at the high end, and the "jocular, familiar," and "grapenutsy" at the low. That description of the folksy, hayseed strain in American fiction is Cather's, but only now revealed, for this year also sees the publication of The Selected Letters of Willa Cather, edited by Andrew Jewell and Janis Stout, an event the strong-minded writer would never have welcomed.

Willa Cather declared in her will that she did not want her letters published or even quoted from and asked her family, friends, and their executors to destroy correspondence from her. It has taken the death of her nephew, Charles Cather, in 2011, and the turning over of her copyrights to the Willa Cather Trust, for her wishes to be flouted.

In their introduction to this big book, Jewell and Stout admit that they "flagrantly defy Cather's will" but give widely assorted reasons for doing so: They say that Cather wrote her will in "the last, dark years of her life" (with darkened judgment?); they observe that anyone who might be hurt by the letters' publication is now dead; that the summaries of Cather's letters (which were permitted) were inadequate and misleading; and that as Cather did not cause her letters to be "systematically" destroyed, the great number of letters still extant suggest she didn't really intend them to disappear. They say that, all told, Cather and her writing, including her letters, are part of our cultural history and "belong to something greater than herself." This last, in my view, is the only justification we need. The publication of Willa Cather's letters, like other contraventions of writers' wishes (the many biographies of George Orwell being a good example) comes down to the simple fact: the dead belong to the living.

There are many ways to read these rich and varied letters: as expressions of Cather's character, personality, and proclivities; as clues to her artistic development; as the reflections of one of the unacknowledged pioneers of modernism; as a portrait of an independent woman at a time when the species was rare; and as an inside look at the world of letters and publishing in the first half of the twentieth century. But right now, at the dawn of their public existence, one is inclined to dwell on why Willa Cather didn't want her letters set before us.

Cather caused some letters to be destroyed because, as she wrote to Mark deWolfe Howe concerning her correspondence with the elderly Annie Fields, they were "entirely artificial and unrepresentative of me," written out of duty to friendship. "I remember well how I used to struggle to fill out a few pages and say nothing at all." But if similar exercises in page filling still exist they are not in this volume. The letters here boil with feeling, with spontaneous expressions of love, friendship, admiration, triumph, vanity, irritation, sorrow, and loss. Absent, however, are sexual transports or allusions to physical intimacy. While it is clear from the letters that Cather was romantically, sometimes passionately, attracted to women, the closest she comes to anything that might bring a blush into the cheek of a young person is discussing – slave to literature that she is – the difficulties of getting her copy of Alphonse Daudet's "Sappho" returned to her.

Still, the sustained eruption of emotion is surely one reason Cather did not want her letters incorporated into her oeuvre. For one thing, she developed the strong belief – set down for all time in 1922 in the essay "The Novel Démeublé" – that in art, direct description of physical sensations or emotion is but "tasteless amplitude." The surface of literature should be cool, uncluttered, austere, while underneath an ineffable, indescribable urgency of feeling should be present, its direct expression repressed, but divined by the reader. Writing to one of her brothers she noted, "People say I have a 'classic style'. A few of them know it's the heat under the simple words that counts."

Above all, however, her letters, if published, she knew, would stand as a gloss to the stories and novels, detracting from their integrity and indissolubility as art, creating a vitiating sluiceway between her work and her life. Indeed, throughout this volume we find many acid remarks on the intrusiveness of biographers and critics who conflate a writer's work with his or her life. Her distaste for this was aesthetic, personal, and strongly felt; thus she was adamant that her letters to her longtime companion, Edith Lewis, and the love of her life, Isabelle McClung Hambourg, be destroyed.

Be that as it may, I shall just go ahead and conflate the life and the work. In the letters, stronger than the emotions of the moment, is the yearning for culture, fulfillment, and independence that seethes in Cather's fiction, most particularly in the Great Plains trilogy: "O Pioneers!," "My Ántonia," and "The Song of the Lark." The early letters, written when she had escaped to college and thence to Pittsburgh, throb with the intensity of her exhilaration at breaking free of the featureless plains and the alternatives offered by Red Cloud, Nebraska: the cloddish unlettered or the cloying genteel.

Also present is her sense of release from the thralldom of a family intent of making her over; they were good people but constitutionally unable to grasp the nature of her aspirations. "I wanted never, never to come back on Father for anything," she wrote to a brother in her sixties, "nor to ask any of my family to put up a dollar to back a game they didn't understand." Her deep satisfaction in being able to make an independent living – as journalist, teacher, managing editor, and finally novelist – is infectious and thrilling. "O I have grown enamored of liberty!" she wrote from Pittsburgh and her first job (on a ladies' journal). "To be wholly free, to really be of some use somewhere, to do with one's money what one likes, to help those who have helped me, to pay the debts of one's loves and of one's hates!"

Cather's insistence on her own independence picks up extra force as she links it with assertions that art is independent of the concerns and duties of life, and is, indeed, preferable to them: "I have been running away from myself all my life ... and have been happiest when I was running fastest. Those last three winters of my mother's life held me close to myself and to the beginnings of things, and it was like being held against things too sad to live with."

Still, as the years pass the letters show Cather's increasing recognition of the irreconcilability of independence and freedom with fulfilling love. Writing to her brother in her dismay after Isabelle got married, she said, "[L]ife is so awfully one-sided: if you keep free you're too damned free, and if you tie up – why there you are."

Aside from the great matters of life and art, Cather's letters deal the details of publishing her books; others praise fellow writers or thank reviewers – some of whom are good friends and were put up to the job by Cather herself. There are letters lamenting the state of the world and of literature; others encourage aspirant writers to ignore the "conventional machinery" of fiction and follow their own ideas. There are some real scorchers, too, including a tirade on the incompetence of Marguerite Yourcenar's translation of "Death Comes for the Archbishop," a hot denunciation of Houghton Mifflin's buttoned-up Bostonian reluctance to promote Cather's work, and a number of chilly-eyed dissections of obnoxious people. ("I've been doing target practice with a pistol, and I know the day will come when I shall let drive at Tooker. I cannot stand either his information or his nobleness much longer.") There are also missives aplenty in which she complains about her accommodations, health, and certain members of her family. ("Was there ever anybody who could always throw the monkey-wrench into the machine and add a spray of cypress to the holly wreath, like our sister Elsie?")

Throughout the letters Willa Cather shows herself exceedingly jealous of her privacy, and it is clear that she would not rejoice in this collection. But readers will, for it is a truly valuable addition to the world of letters in every sense.

Katherine A. Powers reviews books widely and has been a finalist for the Nona Balakian Citation for Excellence in Reviewing from the National Book Critics Circle. She is the editor of Suitable Accommodations: An Autobiographical Story of Family Life: The Letters of J. F. Powers, 1942–1963.